Apparatus for leaching ores



2 Sheets-Sheet l.

(No Model.)

v S.l B. LADD. APPARATUS PoR LBAGHING oms.

No. 567,144. Patented Sept. 8*, 1896..

Invert/Za r,

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(No Model- S. B. LADD-` APPARATUS FOR LEAGHINGORES No. 567,144.'Patented Selyt. 8', 1896.

STORY B. LADD, OF VASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR OF NrrnnSTATES AONE-HALF TO GEORGE B. CHITTENDEN, OF SAME PLACE.

APPARATUS FORy LEACHING oREs.

SPECIFICATION forming part f Letters Patent 'Na-567,144, dated September8, 1896.

Application filed February 21, 1896. -Scrial No. 580,191. (No model.)

To all whom, t may concern,.-

Beitknown that I, STORY B. LADD, a citizen of the United States,residing at Washington, in the District of Columbia, have inventedcertain new and useful Improvements in Apparatus for the Leaehing ofOres; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same, referencevbeing had to the accompanying drawings, and to letters of reference.marked thereon, which form a part of this specification.

The object of the present invention is to larly applicable to caseswhere a large mass of material has to undergo treatment-as, for example,in the lixiviation of low-grade gold ores by the cyanid processand Wherethe expense of handling material becomes'an important factor withrespect to the commercial working-of the process. The invention applies,generically, to the lixiviation of comminuted or pulverized material ofany character, but it is especially designed for the lixiviation of oresbythe cyanid process and will be described with respect thereto. In thetreatment of ore-pulp or slimes by the cyanid and other like processes alarge amount of material, often of a low grade, has to be subjected tothe action of an aqueous solution of a cyanid orrother solvent, or tothe successive action of a series of solutions. The common course ofprocedure in working the cyanid process on a large scale is to run theore-pulp into large vats and then to cause the proper solutions forleaching out the precious metals to percolate therethrough; for example,first an alkaline solution, when the ore is acid, then astrong'solution, then aweaker solution, and finally water to wash thepulp. The vat is then emptied and relled with fresh ore-pulp; also, thesolvent process is sometimes worked by agitating the pulp and leachingsolution in pans or vessels. Both systems require considerable labor andare intermittent.

Another object of the present invention is to provide means Ato make theextraction process continuous, so that the ore-pulp shall progressivelyand continuously be associated with the solutions or the washings whichmay be necessary for thoroughly exhausting the values from the ore. ThisI accomplish by constructing a leaching-tank in the form of a longtrough, which may be divided by one or more iixed or removable bridgesinto so many trough-sections as are required for the several solutionsor washings when one leaching is not sufficient; or by providing aseries of tanks or troughs operatively arranged with respect to eachother, employing in connection therewith a conveyer for the ore-pulpadapted to continuously feed the pulp with a steady movement through theseveral solutions in an uninterrupted iow through the apparatus tothepoint of discharge without any intermediate stoppage or handling ofthe same whereby the lixiviation of the ore is affected.

For the purpose of rendering the operation continuous provision is madefor a constant drawing off of the charged solution or solutions from theleaching-troughs and an inflow of fresh solution thereto. In the case ofthe first cyanid solution the inflow is preferably at the ore-entranceend of the trough or trough-section and the current is with the ore,thus catching the fine float gold carried by the fresh pulp; but in thesubsequent troughs or trough-sections, and also in the first, ifpreferred, the iniiow of the solution (or washing-water) is preferablymade at the ore-exit end and the outflow of the solution is at theopposite end where fresh ore or pulp is entering the trough or troughsection. Thus, in this latter case, the flow of the solution is oppositeto that of the ore. The fresh cyanid solution lirst acts upon pulp whichis largely leached out, and' as the solution becomes more and morecharged with the gold or precious metals it meets pulp that isprogressively richer in the metals, and the conditions are thereforefavorable for effecting a complete extraction of the precious'metals bythe solvent. As a preferred form of V conveyer, slowly-moving bladestransverse to the trough or tank are used. These blades extend acrossthe tank with just enough room at the sides for clearance, and theyreach from above the surface of the solution down to and into theore-pulp on the bottom of the tank with openings or notches in or alongthe lower part of the blades for the underflow of the solution. Theseblades divide the trough or tank into a number of communicatingdivisions and form what may be called traveling partitions, movingslowly through the trough from end to end thereof. The lower edges ofthese blades are preferably fashioned with rake-teeth, and they open upand rake along the layer of ore-pulp on the bottom of the tank andeffect a slow and progressive movement of the mass with a constantplowing therethrough and exposure of fresh portions thereof to theaction of the solution, while the solution in the tank as the series ofblades move forward has to flow back through the notches or openings inthe bottom of the traveling blades from each of these divisions formedby the blades, respectively, into the adjacent rear division, and thusthere is secured a constant and steady underflow of the solution inclose proximity to the agitated pulp. This flow of the solution is inaddition to and distinct from the flow due to the constant addition offresh solvent at one end of the trough and the drawing off of thecharged solution at the other end thereof; but it will be seen that theunderliow thus effected prevents a mere surface iiow of the solutionfrom one end of the trough to the other. On the contrary, as the flowfrom the respective divisions of the trough is from the bottom and undereach traveling partition or blade the overflow or discharge from thetrough at the end is necessarily of the charged portion of the solution.It will be seen that this method of leaching ores places the ore and thesolvent under perfect control, which is a very great advantage withrespect to the economical leaching of ores. There is an agitation andconstant shifting of the pulp in the solution which very muchaccelerates the action of the solvent and shortens the time requiredtherefor, and the speed of the conveyor can be regulated so that thepulp will not remain in the tank or tanks any longer than is neeessaryand yet long enough for the extraction of all value therefrom. On theother hand, the iiow of the solvent through a tank can be gaged so thatit will issue from the tank fully charged or charged to the degree mostprofitable under all the conditions of the case.

The invention will be fully described, and the novel feature thereof,both of a generic and a specific character, set out in the claims.

In the accompanying drawings, Figure l is a sectional longitudinal viewof an apparatus embodying the present invention. Fig. 2 is a plan viewon a reduced scale. Fig. 3 is a detail cross-section of the trough,showing a chain conveyer therein.

A indicates a settling-tank for the ore-pulp or slimes, from the bottomof which tank the pulp may be elevated by a conveyer i3 and fed into thehead of the leaching-trough or the first section thereof, C. It isimmaterial how the ore-pulp or other material to be lixiviated is fed tothe leaching-trough, whether by automatic feeders or otherwise, thoughpreferably some device that will give a regular and uniform supply ofmaterial to the head of the trough is employed, in order that the flowof the same through the trough may be uniform. In the present case theappaia tus is shown as adapted for the treatment of an ore that is notacid, there being used two eyanid solutions of different strengths, anda .final washing calling for the treatment ol' the ore in threetrough-sections. 'lhethree trough-sections-for the strong cyanidsolution, the weak cyanid solution, and the washing--are indicated,respectively, by J, C', and C2. lf the ore requires the action first ofan alkaline solution, it will be understood that the iirst section ofthe trough is to be supplied with an alkaline solution, and following itthe necessary trouglrseetions for the sucA` ceeding steps. On the otherhand, if the ore treatment requires but a single lixiviating bath and awashing, then there will need to be but two troughs or trough-sections,and the washing operation may be very brief or omitted entirely when notessential to the workin g of the material.

D is an endless-chain eonveyer traversing the entire length of thetrough C C Cf3 and passing around the drums D D2. This conveyor isdriven by power applied to the drum D2 and the motion is very slow, thetravel of the conveyer being gaged with respect to the length of thetrough and the time required for the pulp to remain in the solutions. Acenveyer is preferably employed which parts and breaks up the pulp andstirs it and prevents it from packing, as well as moves it forward, inorder that the action of the solvent on the pulp may be thorough andeffective, and to this end conveyer-blades d with a rake edge areemployed, the notches or spaces d of the rake edge extending up into theblade above the normal level of the pulp mass e on the bottom of thetrough, but preferably not up to the surface of the leaching solution c.The raking-blades should be set so that the teeth of one blade willregister with the open spaces of the preceding blade. The action ofthese raking-blades on the pulp is to open up and disintegrate it, sothat the solvent will have access to all parts of the mass, and at thesame time to feed the pulp mass slowly forward. Moreover, if the pulpaccumulates at any point in the trough and heaps up above the teeth ofthe blades, the impervious upper portion of the blade sweeps the pulpalong and levels it off. The movement of' the blades through theleaching solution, said blades extending aeross the trough from side toside, causes currents of the solution through the rake-teeth openings inclose proximity to the agitated pulp, thereby materially assisting theleaching action of the solvent on the pulp.

F F, Fig. 3, are the endless chains of the conveyer, and f fsupporting-rollers for the IOO IIO

conveyer-blades running on the sides of the trough.

Between the adjacent trough-sections there are bridges G G', over whichthe pulp travels out of one trough and into the next. Thus at the end ofthe rst trough-section C, the, floor of the trough rises on a gentleincline g high enough to clear the surface of the leaching solution, andalso to allow a short drainage slope above the same,and then it descendson an incline g into the next trough-section G. The conveyer, by properguideways H for the same, follows the slopes of the bridge and causesthe pulp to travel up out of one trough and over into the next withoutany interruption in its progress. This forward movement of the pulp is,however, very slow and gradual. The operation of the bridge G is thesame, and likewise that of the final slope G2 at the end of the trough,except that here the pulp finally leaves the trough and may bedischarged into a dump-car or disposed of by conveyers or otherwise. InFig. l portions of the trough are indicated as broken away on account ofthe great length of the same. A pipe S delivers the strong cyanidsolution into the head of the troughsection C, and at the tail end ofthe same there is an overflow S for the charged solution. In the case ofthe trough-section C', as before indicated, thereis preferably asupply-pipe S2 for the fresh cyanid solution at the tail endof thesection and an overflow S3 near the head of the same for the solutioncharged with the precious metals. In the case of the washing-section CVis the wastesupply pipe, and WV the discharge therefrom.

As the leaching operation is continuous, and does not require attentionwhen the operation is once properly adj usted with respect to the speedof the conveyer and the flow of the leaching solutions, the trough maybe closed in, if desired, to prevent the escape of the noxioushydrocyanic-acid gas or the decomposition of the leaching solution byatmospheric causes.

The foregoing is given as an embodiment of the invention in itspreferred form, but it will be understood that the details can bechanged without departing from the invention in its generic aspects, as,for example, it willbe seen that the specific conveyer herein described,though in itself possessing imthat of the others,`and a discharge forthe charged solution from each of the troughs.

2. The combination with a leachin g-trou gh having parallel sides andmeans for maintaining a solution at the desired level therein, of asubstantially horizontal series of blades suspended within and extendingnearly across the trough and so arranged that each blade in the solutionwill extend from the surface of the solution in the trough nearly to thebottom of the layer of solution, and means for effecting a longitudinalmovement between the blades and the trough, whereby there is secured aprogressive feed of ore-pulp through the trough, and a scouring actionof the solution on the ore-pulp due to the underiiow of the solutionbeneath the several blades, as set forth.

3. In a leaching apparatus,a trough divided by one or more bridges intosections, each section having an independent fluid-supply pipe andadapted to hold a solvent or iiuid independent of and different fromthat of the other trough-sections, together with a pulpconveyer adaptedto feed the pulp through the several sections of the trough and over theintervening bridges thereof in a continuous How.

4. In a leaching apparatus, a series of troughs or trough-sections, eachhaving an in dependent supply-pipe for a solvent or fiuid different fromthat of the others, in combination with a common pulp-conveyer adaptedto agitate the pulp in the several troughs or trough-sections and feedthe same in a continuous flow out of and into the several troughs ortrough-sections and successively through the same.

5. In a leaching apparatus, a trough divided by one or more bridges intoa series of troughsections with independent duid-supply pipes for theseveral sections, in combination with an endless-chain conveyerhavin gblades traveling in said trough and adapted to agitate the pulp thereinand feed the same in a continuous flow through the several sections ofthe trough and over the intervening bridges.

6. In a leaching apparatus,atrough divided by one or more bridges havinginclined approaches into a series of trough-sections, in combinationwith an endless-chain conveyer having blades traveling in said trough,and adapted to agitate the pulp therein and feed the same in acontinuous flow through the several sections of the trough and over theintervening bridges.

7. In aleaching apparatus,a trough divided by one or more bridges havinginclined approaches into a series of trough-sections, in combinationwith an endless conveyer having rake-blades traveling in said troughthrough the several sections of the same and over the interveningbridges.

8. The combination with a leaching-trough having an end discharge forthe solution, and means for maintaining the solution in the IOO troughat a normal level, of an endless conveyer adapted to move the pulp alongthe bottom of the trough, said conveyor having rake-edged blades withthe upper portion of the blades impervious and adapted to extend abovethe normal level of the surface of a leaching solution in the trough.

9. The combination with a leaching-trough having parallel sides andmeans for, maintaining a solution at the desired level therein, of asubstantially horizontal series of blades suspended within and extendingnearly across the trough, said blades having a series of openings ornotches along the bottom of each blade, with the blades so arranged thateach blade in the solution will extend from the surface of the solutionin the trough nearly to the bottom of the layer of solution, and meansfor effecting a longitudinal movement between the blades and the trough,whereby there is secured a progressive feed of ore-pulp through thetrough, and a scouring action of the solution on the ore-pulp due to theunderfiow of the solution beneath the blades, as set forth.

l0. The combination with a leaching-trough formed of a series ofsections each adapted to hold an independent body of liquid, of theconveyer and the agitatin g-blades having passage-ways for the underflowof the liquid and adapted to feed the pulp from one section to another,throughout the trough, as set forth.

ll. In a leaching apparatus, a trough having one or more bridgesdividing it into a series of sections, said bridges having an inclinedapproach adapted to serve as a drainage-Hoor for the pulp, combined withan endless eonvcyer having notched blades adapted to agitate the pulpand feed the same through the sections in one direction, and over thebridge or bridges, and leave an opening through the notches above thepulp-bed for the underiiow of fluid in the opposite direction, as setforth.

12. The combination in a leaching apparatus, of a settling-tank, aconveyer for sedimentary matter from the bottom of said tank to the headof a leaching-trough, said trough having an endless conveyer extendingthe length of the same4 and adapted to feed pulp therethrough in asteady iiow, bridges dividing the trough into a seriesof sections,supply-pipes for leaching solution leading into one or more of the firstsections of the trough at one end thereof with an overiiow-diseharge atthe opposite end of each of the same, and a water-pipe leading to thelast section of the trough with an overflow-discharge from the sameopposite to the point of entrance.

In testimony whereof I alx my signature :in presence of two witnesses.

STORY l5. LADD. lVitnesses:

S. G. llorKINs, GEO. M. WHITNEY.

